One interesting plot idea could be that Naruto and Sasuke have to go on a joint quest assigned by the Sage of Six Paths in a dream. They are sent to a parallel universe where the ninja world is ruled by dark forces and they have to find a way to bring back the light. Another idea is that the Sage of Six Paths gives them new powers that they have to master together to defeat an ancient evil that has been awakened. Maybe they also have to deal with their own inner demons during this process as the new powers also come with some psychological challenges.
One plot idea could be that Naruto and Sasuke are sent back in time by the Sage of Six Paths to prevent a great disaster that is going to happen in the future. They have to work together to figure out how to change the course of events while also learning more about the Sage's powers and their own destinies.
One idea could be that Naruto, with the power of the Sage of the Six Paths, gets transported to a different ninja world. There, he has to team up with new and strange characters to fight against an evil force that is threatening both worlds. Maybe this new world has different chakra rules and Naruto has to adapt quickly.
One interesting plot idea could be exploring how the reincarnation affects the balance of power in the Naruto world. Maybe the reincarnated character has unique abilities that disrupt the existing order among the ninja villages.
One interesting plot could be about Naruto exploring more of the Sage of Six Paths' untold teachings. For example, he discovers a new jutsu that was lost in time but was once known to the Sage. This could lead to him becoming even more powerful and facing new threats in the ninja world.
One idea could be exploring the training of Naruto by the Sage of the Six Paths in more detail. Maybe the Sage could teach him some long - lost jutsu. Another idea is to have Naruto travel back in time to the era of the Sage and witness the creation of ninjutsu first - hand.
One idea could be Naruto having to face an ancient evil that threatens to disrupt the balance between the six paths and the avatar world. He might have to learn new jutsu inspired by the avatar elements. Another could be Naruto forming an alliance with avatar characters to fight a common foe, like a powerful dark spirit that can cross between their universes.
Perhaps a plot where Naruto has to teach the Sage of Six Paths Senjutsu to a new generation of ninjas. This could involve dealing with their different learning abilities and personalities, and also facing threats from those who want to misuse this powerful technique. It could also show how Naruto has grown as a teacher and a leader.
One idea could be Naruto traveling to a different universe where the Sage of Six Paths is still alive and they team up to face a new, powerful enemy. Another could be a fusion of their powers in a strange way due to a magical artifact in the crossover world. Maybe Naruto gets to learn new jutsu directly from the Sage in a more in - depth way than he did in the original story.
One idea could be exploring the backstory of the Sage of Six Paths in more detail. Maybe his early life, his training, and how he came to be the powerful figure he is. Another plot could involve a modern - day ninja somehow getting in touch with the power or spirit of the Sage of Six Paths and having to deal with the consequences. For example, they might gain new abilities but also attract dangerous enemies.
Perhaps a fanfiction where Naruto, as the Sage of Six Paths, has to face a new and powerful enemy that threatens the entire ninja world. He would have to use his newfound powers and wisdom to protect everyone.